1. Field of the Invention
The invention relates generally to an implement for automatically milking a dairy animal, such as a cow.
2. Description of the Related Art
European patent EP0360354A1 discloses an implement for automatically milking a cow, which is provided with a robot arm. At an end of the robot arm there is provided a sliding element that is movable relative to the robot arm. At the same end of the robot arm there are provided holders for four teat cups. Each of the teat cups may be connected to a vertically movable cylinder by means of a magnetic coupling. The robot arm is movable and is capable of being brought with the teat cups to under a teat of an udder of the cow to be milked. Subsequently, it is possible to attach one of the teat cups to the teat by moving said teat cup upward by means of the cylinder.
On the sliding element there are provided sensor means determining in each case a position of the next teat to which a teat cup has to be attached. Said sensor means comprise a laser, a mirror, a lens, and a receiver. The laser emits light that is partially reflected by the teat. Via the minor the reflected light is led to the lens that images the light onto the receiver. The sensor is capable of rotating about a vertical axis, so that the laser performs a scanning movement. Sensor electronics are connected to the receiver. The sensor electronics are capable of determining the distance and the angle of the teat relative to the sensor on the basis of a signal from the receiver and on the basis of the momentary angle of the sensor at the moment when the latter receives a signal. Thanks to the scanning movement information regarding the position of the teat is obtained in each case along one (in practice horizontal) line. In order to obtain also information regarding the vertical position, the robot arm with the scanner as a whole performs a vertical movement. On the basis of the distance information thus obtained, the robot arm is moved to the teat.
A drawback of the known milking implement is that moving the robot arm with teat cups towards the teat does not always take place in a reliable manner.